'\" te
.\" Copyright (c) David L. Mills 1992, 1993, 1994, 1995, 1996, 1997
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.\" the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH NTP_ADJTIME 2 "May 13, 2017"
.SH NAME
ntp_adjtime \- adjust local clock parameters
.SH SYNOPSIS
.LP
.nf
#include <sys/timex.h>

\fBint\fR \fBntp_adjtime\fR(\fBstruct timex *\fR\fItptr\fR);
.fi

.SH DESCRIPTION
.LP
The \fBntp_adjtime()\fR function adjusts the parameters used to discipline the
local clock, according to the values in the struct \fBtimex\fR pointed to by
\fItptr\fR. Before returning, it fills in the structure with the most recent
values kept in the kernel.
.sp
.LP
The adjustment is effected in part by speeding up or slowing down the clock, as
necessary, and in part by phase-locking onto a once-per second pulse (PPS)
provided by a driver, if available.
.sp
.in +2
.nf
struct timex {
    uint32_t modes;        /* clock mode bits (w) */
    int32_t  offset;       /* time offset (us) (rw) */
    int32_t  freq;         /* frequency offset (scaled ppm) (rw) */
    int32_t  maxerror;     /* maximum error (us) (rw) */
    int32_t  esterror;     /* estimated error (us) (rw) */
    int32_t  status;       /* clock status bits (rw) */
    int32_t  constant;     /* pll time constant (rw) */
    int32_t  precision;    /* clock precision (us) (r) */
    int32_t  tolerance;    /* clock frequency tolerance
                              (scaled ppm) (r) */
    int32_t  ppsfreq;      /* pps frequency (scaled ppm) (r) */
    int32_t  jitter;       /* pps jitter (us) (r) */
    int32_t  shift;        /* interval duration (s) (shift) (r) */
    int32_t  stabil;       /* pps stability (scaled ppm) (r) */
    int32_t  jitcnt;       /* jitter limit exceeded (r) */
    int32_t  calcnt;       /* calibration intervals (r) */
    int32_t  errcnt;       /* calibration errors (r) */
    int32_t  stbcnt;       /* stability limit exceeded (r) */
};
.fi
.in -2

.SH RETURN VALUES
.LP
Upon successful completion, \fBntp_adjtime()\fR returns the current clock state
(see <\fBsys/timex.h\fR>). Otherwise, it returns \fB\(mi1\fR and sets
\fBerrno\fR to indicate the error.
.SH ERRORS
.LP
The \fBntp_adjtime()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 10n
The \fItptr\fR argument is an invalid pointer.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The \fBconstant\fR member of the structure pointed to by \fItptr\fR is less
than 0 or greater than 30.
.RE

.sp
.ne 2
.na
\fB\fBEPERM\fR\fR
.ad
.RS 10n
The {\fBPRIV_SYS_TIME\fR} privilege is not asserted in the effective set of the
calling process.
.RE

.SH SEE ALSO
.LP
.BR ntp_gettime (2),
.BR privileges (7)
